Rinse the fish fillets under cold water, pat dry, cut into large pieces and place in the food processor. Add the anchovies, egg and mustard and process until slightly chunky.

Season the fish mixture with salt and pepper and stir in breadcrumbs.

Place a pan over medium-high heat and distribute oil in it. Spoon the fish mixture into the pan, divide it into two mounds, and gently flatten each mound into a roughly round patty.

Turn the patties over after 3 to 4 minutes and fry for another 3 to 4 minutes, until golden brown and slightly crispy on the outside. Meanwhile, mix the mayo and sriracha together, thoroughly wash the spinach, bean sprouts, and tomatoes, and slice the tomatoes thinly.

Halve the burger buns and toast the inside in a pan or on a toaster.

Spread the bottom half of the burger buns with sriracha mayo, wash the spinach, distribute it on top, and add one or two tomato slices. Place salmon patties on the burgers, scatter sprouts over them, and top with the second half of the bun.